1. Field of the Invention
The present invention relates to a vaporized fuel treatment apparatus of an internal combustion engine, and more specifically, relates to technology for adjusting purge flow rate purged from a canister to an intake system depending on operating conditions of the internal combustion engine.
2. Description of the Related Art
A vaporized fuel treatment apparatus of an internal combustion engine is heretofore known, in which vaporized fuel from a fuel tank is guided to a canister and adsorbed therein, while a purge control valve in a purge path connecting the canister and the intake system is opened under predetermined operating conditions to purge purged fuel to the intake system, as in the vaporized fuel treatment apparatus of an internal combustion engine disclosed in, for example, Japanese Unexamined Patent Application, First Publication No. 11-62729.
With a vaporized fuel treatment apparatus of an internal combustion engine according to one example of the above described prior art, for example, in the idle operating condition, such as when driving a vehicle, there is a case where a control for reducing fuel consumption by stopping fuel supply to the internal combustion engine to stop the internal combustion engine and inhibit unnecessary idle operation, namely a so-called idle stop, is executed.
At the time of stopping the internal combustion engine, if air flows in via the purge path, the air is compressed, and a so-called dieseling phenomenon may occur. When this dieseling phenomenon occurs, a problem is caused in that unpleasant vibration is generated in the internal combustion engine.
Moreover, at the time of operating the internal combustion engine, a coefficient for restricting the purge flow rate is normally updated for a predetermined period of time, to gradually increase the purge flow rate. However, in the idle operating condition, for example, if the purge flow rate is increased at an updated speed similar to that while driving, there is a possibility that the internal combustion engine rotation speed may be unstable due to the influence of the vaporized fuel.
In view of the above circumstances, it is an object of the present invention to provide a vaporized fuel treatment apparatus of an internal combustion engine, which can prevent occurrence of the dieseling phenomenon and prevent the engine rotation speed from becoming unstable during idle operation.
In order to solve the above described problems and achieve the object, the vaporized fuel treatment apparatus of an internal combustion engine of the present invention according to a first aspect of the invention is characterized in that it comprises a canister (for example, a canister 45 in an embodiment described later) for adsorbing vaporized fuel generated in a fuel tank (for example, a fuel tank 41 in the embodiment described later); a purge control device (for example, ECU 5 in the embodiment described later) for controlling the opening of a purge valve (for example, a purge valve 44 in the embodiment described later) disposed in a path (for example, a purge path 43 in the embodiment described later) connecting the canister and an intake system of an engine (for example, an internal combustion engine body 1 in the embodiment described later); and a stop device (for example, ECU 5 in the embodiment described later) for stopping the internal combustion engine when a stop condition of the internal combustion engine (for example, an idle stop flag F_IDLSTP=1 in the embodiment described later) is established, wherein the purge control device closes the purge valve when the stop condition is established.
According to the vaporized fuel treatment apparatus of the internal combustion engine having the above described construction, for example, even if the operation of the internal combustion engine is stopped by means of idle stop or the like, since the purge valve is closed by the purge control device, air is prevented from flowing in, thereby enabling prevention of the occurrence of the dieseling phenomenon.
Moreover, the vaporized fuel treatment apparatus of the internal combustion engine of the present invention according to a second aspect of the invention is characterized in that it comprises a canister (for example, a canister 45 in an embodiment described later) for adsorbing vaporized fuel generated in a fuel tank (for example, a fuel tank 41 in the embodiment described later); a purge control device (for example, ECU 5 in the embodiment described later) for controlling the opening of a purge valve (for example, a purge valve 44 in the embodiment described later) disposed in a path (for example, a purge path 43 in the embodiment described later) connecting the canister and an intake system of an engine; and an idle detection device (for example, ECU 5 in the embodiment described later) for detecting whether the internal combustion engine is in the idle state or not, wherein the purge control device increases the opening of the purge valve for each predetermined period of time longer than that in the non-idle state, when the idle state is detected by the idle detection device.
According to the vaporized fuel treatment apparatus of the internal combustion engine having the above described construction, when it is determined that the internal combustion engine is in the idle state by the idle detection device, the time period for increasing the opening of the purge valve is made longer, to thereby suppress the vaporized fuel from flowing rapidly, enabling prevention of the internal combustion engine rotation speed from becoming unstable.